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  • Java基础练习(2019-03-11)

    1.输入生日,计算年龄

    import java.text.ParseException;
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import java.util.Scanner;
    
    public class test2 {
        public static void main(String[] args) {
            System.out.println("请输入出生年份:");
            Scanner sc = new Scanner(System.in);
            String birth = sc.next();
            SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd");
            Date date0 = null;
            try {
                date0 = sd.parse(birth);
            } catch (ParseException e) {
                e.printStackTrace();
            }
            Date date1 = new Date();
            //将两个Date类型转换为毫秒值。getTime()
            long time = date0.getTime();
            long time1 = date1.getTime();
            long res = (time1 - time) / 1000 / 60 / 60 / 24 / 365;
    
            System.out.println(res);
    
        }
    
    }
    
    

    2.使用for循环和迭代器遍历集合

    import java.util.ArrayList;
    import java.util.Iterator;
    
    public class test3 {
        public static void main(String[] args) {
            ArrayList<String> stus = new ArrayList<>();
            stus.add("nezha");
            stus.add("wukong");
            stus.add("bajie");
    
            //for
            for (int i = 0; i < stus.size(); i++) {
                System.out.println(stus.get(i));
            }
    
            //增强for
            for (String str:stus
                 ) {
                System.out.println(str);
            }
    
            //使用迭代器
            Iterator<String> iterator = stus.iterator();
            while (iterator.hasNext()){
                String res = iterator.next();
                System.out.println(res);
            }
        }
    }
    
    

    3 try catch finally 中return执行顺序

    public class test4 {
        public static void main(String[] args) {
            int mtd = mtd();
            System.out.println(mtd);
        }
    
        public static int mtd(){
            try{
                return 1;
            }catch (Exception e){
                return 2;
            }finally {
                //如果finally有return,永远返回finally中的return
                return 3;
            }
        }
    }
    
    
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  • 原文地址:https://www.cnblogs.com/hellosiyu/p/12466287.html
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